Efficiency information

Formal Definition

The number displayed is defined as eff= T N T 1 N , for N being the maximum number of threads committed with OMP_NUM_THREADS and Ti begin the time the section took with i threads.

Interpreting efficiency

Efficiency represents scalabilty to many cores. An efficiency close to 100% is desirable, but speedups can happen even with low efficiency. (See speedup)
efficiency>1 implies superscalar speedup. In this case, it is likely that one best solution has been found.

Improving efficiency

Efficiency is affected by multiple parameters. In small programs, removing a parallel section or parallelizing a larger super-section might improve efficiency. Low efficiency can also be caused by contention (speedup<1). In this case, using StripMining and InLocalStorage/OutLocalStorage might mitigate contention and improve efficiency.